Isomerization of 1,1,3,3-Tetrafluoropropene

ABSTRACT

The present invention involves methods for isomerization of 1234zc. Also provided are methods for managing 1,1,3,3-tetrafluoropropene produced as a byproduct in a process for synthesizing trans-1,3,3,3-tetrafluoropropene from 245fa, wherein 1234zc is converted into trans/cis-1234ze with the help of a catalyst in the absence of HF and in an isomerization reactor, or is converted into 1234zc and/or 245fa with the help of a catalyst in the presence of HF in a separate reactor or preferably in the same reactor of 245fa dehydrofluorination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of U.S. ProvisionalApplication No. 61/145,333, filed Jan. 16, 2009, which is incorporatedherein by reference.

BACKGROUND

1. Field of Invention

This invention relates to methods for producing hydrofluorocarboncompounds. More specifically, this invention relates to isomerization ofhydrofluoroalkenes.

2. Description of Prior Art

Currently, there is a worldwide effort to develop hydrofluorocarbons(HFCs), or compounds containing only carbon, hydrogen and fluorine, forapplications as refrigerants, blowing agents, solvents and diluents forgaseous sterilization. Unlike chlorofluorocarbons (CFCs) andhydrochlorofluorocarbons (HCFCs), both of which potentially damage theEarth's ozone layer, HFCs contain no chlorines and thus pose no threatto the ozone layer. In this regard, trans-1,3,3,3-tetrafluoropropene(trans-1234ze) is a compound that has the potential to be used as a zeroOzone Depletion Potential (ODP) and a low Global Warming Potential (GWP)refrigerant, blowing agent, aerosol propellant, solvent, etc., and alsoas a fluorinated monomer.

Methods for producing HFO-1234ze are known. For example, U.S. Pat. No.5,710,352 teaches the fluorination of 1,1,1,3,3-pentachloropropane(HCC-240fa) to form HCFO-1233zd and a small amount of HFO-1234ze. U.S.Pat. No. 5,895,825 teaches the fluorination of HCFO-1233zd to formHFO-1234ze. U.S. Pat. No. 6,472,573 also teaches the fluorination ofHCFO-1233zd to form HFO-1234ze. U.S. Pat. No. 6,124,510 teaches theformation of cis and trans isomers of HFO-1234ze by thedehydrofluorination of HFC-245fa using either a strong base or achromium-based catalyst in the presence of an oxygen containing gas.U.S. Pat. No. 7,563,936, which is incorporated herein as a reference,teaches the isomerization of cis-1234ze into trans-1234ze overjudiciously selected isomerization catalysts. U.S. Pat. No. 7,485,760,incorporated herein as a reference, further discloses an integratedprocess to produce trans-1234ze from 245fa, which comprises: (a)dehydrofluorinating 1,1,1,3,3-pentafluoropropane to thereby produce aresult comprising cis-1,3,3,3-tetrafluoropropene,trans-1,3,3,3-tetrafluoropropene and hydrogen fluoride; (b) optionallyrecovering hydrogen fluoride from the result of step (a); (c)isomerizing at least a portion of the cis-1,3,3,3-tetrafluoropropeneinto trans-1,3,3,3-tetrafluoropropene; and (d) recoveringtrans-1,3,3,3-tetrafluoropropene. In one preferred embodiment of thatdisclosure, 245fa dehydrofluorination and cis-1234ze isomerization arecombined in one reactor vessel and after HF is recovered trans-1234ze isisolated as purified product from the overhead of a distillation columnand the mixture of unconverted 245fa and cis-1234ze collected as heaviesin the reboiler is recycled back to the reactor.

SUMMARY OF THE INVENTION

Applicants have discovered that small amounts of1,1,3,3-tetrafluoropropene (1234zc) are also generated during 245fadehydrofluorination and remained in the heavies. When 1234zc isaccumulated to certain amounts it becomes difficult to remove bytraditional distillation methods. Due to its unknown toxicity andaccumulation in the heavies without an outlet, 1234zc has to be removedfrom the reaction system. Applicants have come to appreciate the needfor means by which 1234zc can be removed with minimum loss of productyield and have developed processes for converting 1234zc into usefulproducts (e.g., 1234ze and 245fa) via isomerization and/or fluorinationin efficient and cost effective manners. The present inventionadvantageously manages 1234zc generated as by-product in thetrans-1234ze manufacturing process by converting the 1234zc into atleast one of 1234ze and/or 245fa.

Accordingly, one aspect of the present invention provides a method forisomerizing a compound comprising contacting a composition comprising1,1,3,3-tetrafluoropropene with at least one isomerization catalystselected from the group consisting of metal halides, halogenated metaloxides, and zero-valent metals or metal alloys, wherein said contactingoccurs at a reaction temperature sufficient to isomerize at least aportion of said 1,1,3,3-tetrafluoropropene into1,3,3,3-tetrafluoropropene.

In another aspect of the invention, provided is a method for producingtrans-1,3,3,3-tetrafluoropropene comprising: (a) reacting ahydrofluorocarbon reactant in a first reactor under conditions effectiveto produce product stream comprising trans-1,3,3,3-tetrafluoropropene,cis-1,3,3,3-tetrafluoropropene, 1,1,3,3-tetrafluoropropene, and hydrogenfluoride, and unconverted hydrofluorocarbon reactant; (b) optionallyremoving said generated hydrogen fluoride from said product stream; (c)distilling said product stream to produce a purified product streamcomprising said trans-1,3,3,3-tetrafluoropropene and a second streamcomprising said cis-1,3,3,3-tetrafluoropropene, said1,1,3,3-tetrafluoropropene, and said unconverted hydrofluorocarbonreactant; (d) contacting said second stream with at least oneisomerization catalyst selected from the group consisting of metalhalides, halogenated metal oxides, and zero-valent metals or metalalloys, wherein said contacting occurs at a reaction temperaturesufficient to isomerize at least a portion of said1,1,3,3-tetrafluoropropene into isomerized 1,3,3,3-tetrafluoropropene;and optionally (e) recirculating said isomerized1,3,3,3-tetrafluoropropene to said first reactor.

In another aspect of the invention, provided is a method for producing afluorinated compound comprising reacting a composition comprising1,1,3,3-tetrafluoropropene with hydrogen fluoride in the presence of atleast one catalyst selected from the group consisting of metal halidesand halogenated metal oxides wherein said reacting occurs at a reactiontemperature sufficient to convert at least a portion of said1,1,3,3-tetrafluoropropene into a reaction product comprising at leastone of 1,3,3,3-tetrafluoropropene and 1,1,1,3,3-pentafluoropropane.

In yet another aspect of the invention, provided is a method forproducing trans-1,3,3,3-tetrafluoropropene comprising: (a) reacting ahydrofluorocarbon reactant in a first reactor under conditions effectiveto produce product stream comprising trans-1,3,3,3-tetrafluoropropene,cis-1,3,3,3-tetrafluoropropene, 1,1,3,3-tetrafluoropropene and hydrogenfluoride, and unconverted hydrofluorocarbon reactant; (b) optionallyremoving said generated hydrogen fluoride from said product stream; (c)distilling said product stream to produce a purified product streamcomprising said trans-1,3,3,3-tetrafluoropropene and a second streamcomprising said cis-1,3,3,3-tetrafluoropropene, said1,1,3,3-tetrafluoropropene, and said unconverted hydrofluorocarbonreactant; and (d) contacting said second stream with HF in the presenceof at least one catalyst selected from the group consisting of metalhalides and halogenated metal oxides, wherein said contacting occurs ata reaction temperature sufficient to convert at least a portion of said1,1,3,3-tetrafluoropropene into a recycle product comprising at leastone of 1,3,3,3-tetrafluoropropene and 1,1,1,3,3-pentafluoropropane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a process for converting 245fa into1234ze according to a preferred embodiment of the invention, wherein a1234zc byproduct is isomerized before being recirculated to adehydrofluorination reactor.

FIG. 2 is a schematic depiction of a process for converting 245fa into1234ze according to a preferred embodiment of the invention, wherein a1234zc byproduct is isomerized and/or fluorinated in the presence of HFbefore being recirculated to a dehydrofluorination reactor.

FIG. 3 is a schematic depiction of a process for converting 245fa into1234ze according to a preferred embodiment of the invention, wherein a1234zc byproduct is isomerized and/or fluorinated after beingrecirculated to a dehydrofluorination reactor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention discloses methods for isomerizing1,1,3,3-tetrafluoropropene and methods for managing1,1,3,3-tetrafluoropropene in trans-1,3,3,3-tetrafluoropropenemanufacturing process. In a preferred embodiment, 1234zc is convertedinto trans/cis-1234ze with the help of a catalyst in the absence of HFin a separate isomerization reactor. In another preferred embodiment,1234zc is converted into 1234ze and/or 245fa with the help of a catalystin the presence of HF in a separate reactor or, more preferably, in thesame reactor of 245fa dehydrofluorination.

A. 1234zc Isomerization in the Absence of HF

Referring to FIG. 1, a method of producing trans-1234ze from 245faaccording to the present invention is shown. Here, the method involves arecycle loop wherein 1234zc byproduct, along with unreacted 245fa,cis-1234ze are collected as heavies in a reboiler of a distillationcolumn and then fed into an isomerization reactor (Reactor 2) where the1234zc is converted into trans/cis-1234ze with the help of anisomerization catalyst and in the absence of HF before being recycledback to the reactor of 245fa dehydrofluorination (Reactor 1), preferablya vapor-phase reactor. Three classes of catalysts for this 1234zcisomerization reaction are described as follows:

The first class of isomerization catalysts is metal halides, preferablymono-, bi-, tri-, and tetra-valent metal halides and theirmixtures/combinations, more preferably bi-, tri-, and tetra-valent metalhalides and their mixtures/combinations, and most preferably tri- andtetra-valent metal halides and their mixtures/combinations. Componentmetals include, but are not limited to, Ti⁴⁺, Zr⁴⁺, Ce⁴⁺, Cr³⁺, Al³⁺,Fe³⁺, Mg²⁺, Ca²⁺, Ni²⁺, Zn²⁺, Pd²⁺, Li⁺, Na⁺, K⁺, and Cs⁺. Componenthalogens include, but are not limited to, F⁻, Cl⁻, Br⁻, and I⁻. Thecatalyst may be supported or unsupported.

The second class of catalysts is halogenated metal oxides, preferablyhalogenated mono-, bi-, tri-, and tetra-valent metal oxides and theirmixtures/combinations, more preferably halogenated bi-, tri-, andtetra-valent metal oxides and their mixtures/combinations, and mostpreferably halogenated tri- and tetra-valent metal oxides and theirmixtures/combinations. Component metals include, but are not limited to,Ti⁴⁺, Zr⁴⁺, Ce⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Mg²⁺, Ca²⁺, Ni²⁺, Zn²⁺, Pd²⁺, Li⁺,Na⁺, K⁺, and Cs⁺. Halogenation treatments can include any of those knownin the prior art, particularly those that employ HF, F₂, HCl, Cl₂, HBr,Br₂, HI, and I₂ as the halogenation source. The catalyst may besupported or unsupported.

The third class of catalysts is neutral, i.e., zero valent, metals,metal alloys and their mixtures. Useful metals include, but are notlimited to, Pd, Pt, Rh, Fe, Co, Ni, Cu, Mo, Cr, Mn, and combinations ofthe foregoing as alloys or mixtures. The catalyst may be supported orunsupported.

The isomerization reaction is preferably carried out in a gas phase. Inless preferred embodiments, it is possible to carry out such reaction ina liquid phase.

Desirable levels of 1234zc conversion and 1234ze selectivity can beimpacted by operating parameters, including conditions such as reactiontemperature, pressure, and residence time. The reaction will be carriedout at conditions sufficient to effect 1234zc isomerization. Selectivityfor the isomerization reaction to 1234ze with the preferred catalysts isabout 50% or more, more preferably about 70% or more, and mostpreferably about 95% or more. Conversion of 1234zc is preferably about10% or more, more preferably about 50% or more, and most preferablyabout 95% or more.

Isomerization can be carried out at a temperature sufficient to achievedesired conversion level. Reaction temperature refers to the averagetemperature in the catalyst bed. The reaction temperature preferablyranges from about 50° C. to about 400° C., more preferably from about100° C. to about 350° C., and most preferably from about 120° C. toabout 300° C.

Isomerization can be carried out over a wide range of pressures, aspressure is not a particularly critical reaction condition. Reactorpressure can be superatmospheric, atmospheric, or under vacuum. Inpreferred embodiments however, the reaction is carried out underpressure conditions ranging from about 1 to about 20 atm and morepreferably from about 2 to about 6 atm.

Isomerization can be carried out over a wide range of residence times,as residence time is not a particularly critical reaction condition. Inpreferred embodiments however, residence time may range from about 0.5second to about 600 seconds and more preferably from about 10 to about60 seconds.

B. 1234zc Isomerization and/or Fluorination in the Presence of HF

Referring to FIG. 2, the mixture of 245fa, cis-1234ze, and 1234zc arecollected as heavies in a reboiler of distillation column and are co-fedtogether with HF into a separate reactor (Reactor 2) to convert 1234zcinto 1234ze and/or 245fa with the help of a catalyst before beingrecycled back to the reactor of 245fa dehydrofluorination (Reactor 1).Here, a derivate of said bottoms stream is recycled to Reactor 1. FIG. 3shows another embodiment, which is more preferred, wherein the mixtureof 245fa, cis-1234ze, and 1234zc is directly recycled back to thereactor of 245fa dehydrofluorination, in which 1234zc is converted into1234ze and/or 245fa by reacting with HF (which is generated from 245fadehydrofluorination in this case) with the help of a catalyst. In thiscase, the conversion of 1234zc to either 245fa or 1234ze is conductedunder the same or similar conditions (catalyst, temperature, pressure,and residence time) as those used in the 245fa to 1234ze conversion.Generally, these reaction parameters are within the ranges cited for theembodiments using FIG. 1 or FIG. 2.

Two classes of catalysts for this 1234zc isomerization reaction aredescribed as follows:

The first class of catalysts is metal halides, preferably mono-, bi-,tri-, and tetra-valent metal halides and their mixtures/combinations,more preferably bi-, tri-, and tetra-valent metal halides and theirmixtures/combinations, and most preferably tri- and tetra-valent metalhalides and their mixtures/combinations. Component metals include, butare not limited to, Ti⁴⁺, Zr⁴⁺, Ce⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Mg²⁺, Ca²⁺,Ni²⁺, Zn²⁺, Pd²⁺, Li⁺, Na⁺, K⁺, and Cs⁺. Component halogens include, butare not limited to, F⁻, Cl⁻, Br⁻, and I⁻. The catalyst may be supportedor unsupported.

The second class of catalysts is halogenated metal oxides, preferablyhalogenated mono-, bi-, tri-, and tetra-valent metal oxides and theirmixtures/combinations, more preferably halogenated bi-, tri-, andtetra-valent metal oxides and their mixtures/combinations, and mostpreferably halogenated tri- and tetra-valent metal oxides and theirmixtures/combinations. Component metals include, but are not limited to,Ti⁴⁺, Zr⁴⁺, Ce⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Mg²⁺, Ca²⁺, Ni²⁺, Zn²⁺, Pd²⁺, Li⁺,Na⁺, K⁺, and Cs⁺. Halogenation treatments can include any of those knownin the prior art, particularly those that employ HF, F₂, HCl, Cl₂, HBr,Br₂, HI, and I₂ as the halogenation source. The catalyst may besupported or unsupported.

The isomerization and/or fluorination reaction is preferably carried outin a gas phase. In less preferred embodiments, it is possible to carryout such reaction in a liquid phase.

Desirable levels of 1234zc conversion and 1234ze and/or 245faselectivity can be impacted by operating parameters, includingconditions such as reaction temperature, feed composition, pressure, andresidence time. The reaction will be carried out at conditionssufficient to effect 1234zc isomerization and/or fluorination.Selectivity for the isomerization and/or fluorination reaction to 1234zeand/or 245fa with the preferred catalysts is about 50% or more, morepreferably about 70% or more, and most preferably about 95% or more.Conversion of 1234zc is preferably about 10% or more, more preferablyabout 50% or more, and most preferably about 95% or more.

Isomerization and/or fluorination can be carried out at a temperaturesufficient to achieve desired conversion level. Reaction temperaturerefers to the average temperature in the catalyst bed. The reactiontemperature preferably ranges from about 100° C. to about 500° C., morepreferably from about 200° C. to about 400° C., and most preferably fromabout 250° C. to about 300° C. The ratio of 1234zc to HF in the feedpreferably ranges from 1:0.1 to 1:10000, more preferably from 1:1 to1:2000, and most preferably from 1:10 to 1:1500.

Isomerization and/or fluorination can be carried out over a wide rangeof pressures, as pressure is not a particularly critical reactioncondition. Reactor pressure can be superatmospheric, atmospheric, orunder vacuum. In preferred embodiments however, the reaction is carriedout under pressure conditions ranging from about 1 to about 20 atm andmore preferably from about 2 to about 6 atm.

Isomerization and/or fluorination can be carried out over a wide rangeof residence times, as residence time is not a particularly criticalreaction condition. In preferred embodiments however, residence time mayrange from about 0.5 second to about 600 seconds and more preferablyfrom about 10 to about 60 seconds.

EXAMPLES

The following examples are served to demonstrate that 1234zc can beconverted into 1234ze and/or 245fa through the process disclosed in thepresent invention.

Example 1 1234zc Isomerization in the Absence of HF Over FluorinatedCr₂O₃ Catalyst

A Monel tube reactor (0.75″OD×0.625″ID×23.0″L) was charged with 20 ml ofcatalyst pellets. The reactor was heated by a 12″ split tube furnace. Amulti-point thermocouple, inserted through catalyst bed, was used tomeasure the temperature of catalyst bed. A mixture of trans-1234ze,1234zc, cis-1234ze, and 245fa was passed over this catalyst at a rate of12 g/h. The reaction was conducted under 0.0 psig and at a temperaturethat was low enough to make certain that no reaction would occur to245fa included in the feed. The effluent was analyzed by an on-line GCto determine 1234zc conversion and 1234ze selectivity.

The catalyst used in Example 1 was fluorinated Cr₂O₃ catalyst. As shownin Table 1, at both 100° C. and 150° C., compared to feed compositions,the concentrations of both trans-1234ze and cis-1234ze in product streamwere increased while the concentration of 1234zc was decreasedaccordingly and the concentration of 245fa remained almost unchanged,indicating the occurrence of 1234zc isomerization into 1234ze. Theconversion of 1234zc at 100 and 150° C. was 58.39 and 100.00%,respectively, and the selectivity to 1234ze was 100.00% in bothtemperatures. These results indicate that the fluorinated chromiacatalyst is not only active but also selective for 1234zc isomerizationinto 1234ze in the absence of HF.

Example 2 1234zc Isomerization/Fluorination in the Presence of HF OverFluorinated Cr₂O₃ Catalyst

A Monel tube reactor (2″ID×36″L) was charged with 760 ml of catalystpellets. The reactor was heated by a sand bath furnace. A multi-pointthermocouple, inserted through catalyst bed, was used to measure thetemperatures of catalyst bed. A mixture of trans-1234ze, 1234zc,cis-1234ze, and 245fa was passed over this catalyst at a rate of 1.8lb/h. The reaction was conducted under 5.2 psig and at 250-280° C.,which was high enough for 245fa dehydrofluorination to produce 1234zeand HF. Both the feed and the effluent were analyzed by GC to determinethe concentrations of 1234zc at the inlet and outlet of reactor.

The catalyst used in Example 2 was fluorinated Cr₂O₃ catalyst. As shownin Table 2, at 250-280° C., the concentration of 1234zc was, on average,33% lower at reactor outlet than at reactor inlet, indicating theoccurrence of 1234zc isomerization into 1234ze and/or 1234zcfluorination into 245fa by reacting with HF (which is generated from245fa dehydrofluorination). These results indicate that it is feasibleto keep 1234zc within the recycle loop and avoid accumulation of 1234zein the recycle stream.

Having thus described a few particular embodiments of the invention,various alterations, modifications, and improvements will readily occurto those skilled in the art. Such alterations, modifications, andimprovements, as are made obvious by this disclosure, are intended to bepart of this description though not expressly stated herein, and areintended to be within the spirit and scope of the invention.Accordingly, the foregoing description is by way of example only, andnot limiting. The invention is limited only as defined in the followingclaims and equivalents thereto.

TABLE 1 1234zc isomerization in the absence of HF over fluorinatedchromia catalyst Feed composition Product Composition mol, % Temp. mol,% 1234zc 1234ze t-1234ze 1234zc c-1234ze 245fa others (° C.) t-1234ze1234zc c-1234ze 245fa others conv., % sel., % 81.22 2.02 14.00 2.68 0.06100 81.82 0.84 14.68 2.63 0.03 58.39 100.00 81.22 2.02 14.00 2.68 0.06150 82.62 0.00 14.64 2.69 0.05 100.00 100.00

TABLE 2 1234zc isomerization/fluorination in the presence of HF overfluorinated chromia catalyst Feed composition Product Composition Timeppm ppm % % ppm % ppm % % ppm h t-1234ze 1234zc c-1234ze 245fa otherst-1234ze 1234zc c-1234ze 245fa others 0.7 972 489 34.16 65.55 1383 63.86394 12.87 23.05 1342 2.7 893 504 34.34 65.38 1419 60.53 324 11.97 27.301311 4.7 479 452 33.42 66.36 1316 58.72 296 11.47 29.61 1412 6.7 686 52534.53 65.21 1439 58.34 295 11.39 30.07 1376 8.7 432 430 33.47 66.30 146158.04 289 11.32 30.46 1363 10.7 382 419 32.81 66.96 1508 57.84 291 11.2930.67 1453 12.7 741 468 34.3 65.38 1951 58.12 290 11.33 30.35 1504 14.7500 397 33.64 66.10 1635 58.49 296 11.52 29.78 1623 16.7 440 430 33.5266.23 1648 58.24 292 11.40 30.14 1668 18.7 691 447 33.79 65.92 177058.23 293 11.39 30.14 1706 20.7 971 463 33.96 65.71 1878 58.10 294 11.3830.29 1741

1. A method for isomerizing a compound comprising: contacting acomposition comprising 1,1,3,3-tetrafluoropropene with at least oneisomerization catalyst selected from the group consisting of metalhalides, halogenated metal oxides, and zero-valent metals or metalalloys, wherein said contacting occurs at a reaction temperaturesufficient to isomerize at least a portion of said1,1,3,3-tetrafluoropropene into 1,3,3,3-tetrafluoropropene.
 2. Themethod of claim 1 wherein said 1,3,3,3-tetrafluoropropene istrans-1,3,3,3-tetrafluoropropene.
 3. The method of claim 1 wherein said1,3,3,3-tetrafluoropropene is cis-1,3,3,3-tetrafluoropropene.
 4. Themethod of claim 1 wherein said 1,3,3,3-tetrafluoropropene is a mixtureof cis-1,3,3,3-tetrafluoropropene and trans-1,3,3,3-tetrafluoropropene.5. The method of claim 1 wherein said composition further comprisescis-1,3,3,3-tetrafluoropropene and/or 1,1,1,3,3-pentafluoropropane priorto said contacting.
 6. The method of claim 1 wherein said isomerizationis at least about 95% selective for 1,3,3,3-tetrafluoropropene.
 7. Themethod of claim 1 wherein said isomerization coverts at least about 95%of said 1,1,3,3-tetrafluoropropene.
 8. The method of claim 1 whereinsaid reaction temperature is from about 120 to about 300° C.
 9. Themethod of claim 1 wherein said pressure is about 2 to about 6 atm. 10.The method of claim 1 wherein said residence time is about 10 to about60 seconds.
 11. A method for producing trans-1,3,3,3-tetrafluoropropenecomprising: reacting a hydrofluorocarbon in a first reactor underconditions effective to produce product stream comprisingtrans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene,1,1,3,3-tetrafluoropropene, hydrogen fluoride, and unconvertedhydrofluorocarbon reactant; optionally removing said generated hydrogenfluoride from said product stream; distilling said product stream toproduce a purified product stream comprising saidtrans-1,3,3,3-tetrafluoropropene and a second stream comprising saidcis-1,3,3,3-tetrafluoropropene, said 1,1,3,3-tetrafluoropropene, andsaid unconverted hydrofluorocarbon reactant; contacting said secondstream with at least one isomerization catalyst selected from the groupconsisting of metal halides, halogenated metal oxides, and zero-valentmetals or metal alloys, wherein said contacting occurs at a reactiontemperature sufficient to isomerize at least a portion of said1,1,3,3-tetrafluoropropene into isomerized 1,3,3,3-tetrafluoropropene;and optionally recirculating said isomerized 1,3,3,3-tetrafluoropropeneto said first reactor.
 12. The method of claim 11 wherein saidhydrofluorocarbon comprises 1,1,1,3,3-pentafluoropropane.
 13. A methodfor producing a fluorinated compound comprising: reacting a compositioncomprising 1,1,3,3-tetrafluoropropene in the presence of hydrogenfluoride and at least one catalyst selected from the group consisting ofmetal halides and halogenated metal oxides wherein said reacting occursat a reaction temperature sufficient to convert at least a portion ofsaid 1,1,3,3-tetrafluoropropene into a reaction product comprising atleast one of 1,3,3,3-tetrafluoropropene and1,1,1,3,3-pentafluoropropane.
 14. The method of claim 13 wherein saidreaction product comprises 1,3,3,3-tetrafluoropropene.
 15. The method ofclaim 13 wherein said reaction product comprises1,1,1,3,3-pentafluoropropane.
 16. The method of claim 13 wherein saidreacting comprises forming a reaction mixture comprising1,1,3,3-tetrafluoropropene and hydrogen fluoride in a1,1,3,3-tetrafluoropropene:hydrogen fluoride ratio of about 1:10 toabout 1:1500.
 17. The method of claim 13 wherein said reactiontemperature is from about 250 to about 300° C.
 18. The method of claim13 wherein said reacting occurs in a vapor phase.
 19. A method forproducing trans-1,3,3,3-tetrafluoropropene comprising:dehydrofluorinating a hydrofluorocarbon reactant in a first reactorunder conditions effective to produce reaction product stream comprisingtrans-1,3,3,3-tetrafluoropropene, cis-1,3,3,3-tetrafluoropropene,1,1,3,3-tetrafluoropropene, hydrogen fluoride, and unconvertedhydrofluorocarbon reactant; optionally removing said generated hydrogenfluoride from said product stream; distilling said reaction product toproduce a purified product stream comprising saidtrans-1,3,3,3-tetrafluoropropene and a second stream comprising saidcis-1,3,3,3-tetrafluoropropene, said 1,1,3,3-tetrafluoropropene, andunconverted hydrofluorocarbon reactant; recirculating said secondstream, or derivative thereof, to said first reactor; and contactingsaid second stream with at least one catalyst selected from the groupconsisting of metal halides and halogenated metal oxides, wherein saidcontacting occurs in the presence of hydrogen fluoride and at a reactiontemperature sufficient to convert at least a portion of said1,1,3,3-tetrafluoropropene into at least one of1,3,3,3-tetrafluoropropene and 1,1,1,3,3-pentafluoropropane.
 20. Themethod of claim 19 wherein said contacting occurs in a second reactor.21. The method of claim 19 wherein contacting occurs in said firstreactor.